Rowi description

Formerly considered a subspecies of the North Island brown kiwi (Apteryx mantelli), the rowi is the most recently described kiwi, a group of iconic flightless birds from New Zealand (3). Evolving in the absence of mammals, these distinctive birds have adapted to a ground-dwelling life, with stout, powerful legs and a cryptic plumage of spiky, brown feathers. The breastbone, to which the flight muscles attach in other birds, has been lost, and the wings have become greatly reduced. External nostrils, uniquely positioned at the end of the long, curved bill, also provide kiwis with a highly developed sense of smell (4). The rowi is distinguished from other kiwis by a greyer colour, often with white patches around the face, and softer feathers (5).

Related species

Rowi biology

Kiwis are nocturnal birds, spending the day resting in burrows dug into the ground with powerful claws. Shortly after sunset, kiwis emerge to forage for insects, snails, spiders, earthworms and fallen fruits on the forest floor (3)(7). Insect prey is found by tapping and sniffing the ground, followed by plunging the long beak into the earth, stabbing back and forth to catch underground quarry. Food is subsequently picked up with the tip of the bill, and thrown to the back of the throat with quick jerks (4).

In common with other kiwis, the rowi is strictly monogamous, forming permanent pair bonds. Partners fiercely defend territories of around one square kilometre, using olfactory communication, vocal displays, and occasionally physical battles. The male in particular will vigorously repel strange birds, often inflicting wounds on the intruder (3)(4)(7).

The rowi breeds between June and February, with pairs commencing courtship displays of running and chasing, and loud grunting and snorting (4)(5). Usually a single, exceptionally large egg is laid, which may weigh as much as a quarter of the female’s weight, and both parents alternate incubation duties for some 65 to 90 days (4). During this time, the parents shed feathers from the breast, leaving a naked patch that is thought to help transfer heat to the egg. Once hatched, the well developed, fully feathered chicks venture out of the nest to feed themselves, becoming independent at two to seven weeks old. The juveniles grow slowly, taking three to five years to reach adult size, but once maturity is reached, survival in the rowi is exceptionally high, with a life expectancy of over 56 years and some birds living up to a remarkable 100 years old (2)(7).

Rowi range

Endemic to south Okarito forest in west South Island, New Zealand, the rowi has an extremely small range of only ten square kilometres (2)(5). Historically, the rowi was found across northern South Island and southern North Island, but it has probably been restricted to its present distribution since the late 1800s (3).

Rowi status

Rowi threats

Like all kiwis, the rowi has suffered from the destructive activities of human settlers on New Zealand. Hunting, habitat loss and predation by dogs were the likely agents of initial declines; however, the arrival of Europeans in the mid-1800s and subsequent introduction of mammalian predators, particularly stoats, accelerated the decline. Kiwis evolved on islands that lacked terrestrial predators and consequently are extremely vulnerable to predation (3). Predation by stoats is undoubtedly the major factor behind the recent declines in the rowi population, with stoats being responsible for at least half the deaths of rowi chicks, and only ten percent of chicks surviving to adulthood (3)(6). Consequently, the rowi population has crashed, reaching a critically low number of around 150 birds in the mid-1990s. Predation by stoats in Okarito forest is further complicated by fluctuations in the productivity of native tree species, with peaks in fruiting causing occasional plagues of stoats, hindering conservation efforts (2)(3). The rowi is further threatened by predation by cats and dogs, road collisions, and by introduced possums, which enter burrows to take eggs and chicks (5).

Rowi conservation

Kiwi conservation began in 1991, when the New Zealand Government’s Department of Conservation published the first kiwi recovery plan. Initial conservation measures focused on determining the status of each species and the reasons behind population declines. This was followed by intensive trapping efforts to remove predators and the establishment of five kiwi sanctuaries, including the Okarito sanctuary, which encompasses the rowi’s range (3). Operation Nest Egg was then developed, which began the removal of rowi eggs from the wild to Willowbank Wildlife Reserve, where the chicks hatch and grow before being transferred to the predator-free island of Motuara. Once big enough to defend themselves from predators, the birds are then released back into Okarito forest and monitored through radio transmitters (5). As a direct result of these efforts, the rowi population has increased to around 250 and is predicted to increase to 600 by 2018 (3). Furthermore, public awareness and concern for the welfare of kiwis has increased substantially over recent years, and there is much hope that with the continuation and success of conservation efforts, the future of this charismatic bird will be secured (5).

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